Telegraphy.



L.- M. POTTS.

TELEGBAPHY. 'APPLIOATIOI FILED IALQ, 1907. RENEWED APR. 10, 1908.

901,372. I Patented 0ct.20,1908.

a SHEETFBEBET 2.

2e t fil a isc'onnected to these lines in such a* m nner that the outgoing current from the STATES PATENTDFFIOE.

Louisa} PQTTS; F BALTIMORE, MARYLAND, ASSIGNOR TO-THEROWLAN TELEGRAPHIC COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF NEW JERSEY.

- maxim.

Na-901,372.; i

v v Specification of Letters Patent.

. Fatented'Oct. 2o, '19os.

: mats mas-m, 1907, Serial No. ae1, 53o. Renewed April 10,1908. semi No. 488,818. 1

To "la concern: l Be it'knownt Ml, :IJOUISMMPOTTS a citizen of the United States, residing-at Baltiw more; city, in the State of Maryland, have in- 5 vcntdcert ain new and useful Improvements in Te legrap hmland I d -herebydeclare the following to be a full, clear, and exact description or the invention, such as will enable others skilled in the 'art to which it appertains tornake anduse the same.

f Thisinvnt'on relates toa method *ef bal-' ancing' the'lines of electric circuits and par ticularly'ltd' the" balancing of the lines emp1 ed'in duple ji systems of telegraphy. Iuos t systems of telegrap sages are tralns'mitted in opposite directions simultanequsly flt is'necessary that the signs; s tifansmitted from the station shall I haveffno efiect upfonfthe receiving rela at said station,thisrelaybein controlle enft'irely by thefincomingsign from the distant station; For this'purpose'an artificial line'is' employed at the station which is made tohave" all the electrical characteristics of line. A relay having two identical transmitting-station passes through" one windingto the real, line and through the others hiding in the opposite direction to the "fartificiaflinefi When the artificial line has: been'i'so "adjusted that the same amount of current"- asses through both coils there will be new e 'ect producedby the -Out 'oing currentupon'the-relay; This metho is-some- J times modified by substituting for the O positely wbund coils of the relay two equa resistances and connecting'a single wound relay across from the be inning of the real line 40 to the be innin' of' te artificial line. In 'this case 5:50, w en e ual and like currents. pass through therea and artificial lines there isno effect of the outgoing current upon -the rela the outgoing signals u on the relay and then v to-'adjust-;the artificia line until no effect is produced "on the relay, or as smallvaneffect as may be necessarytoinsure good reception.

' The present invention furnlshes a method.

of not enly' indicating when the'balance has been obtainedbetween the realandthe artias; it a showing the state of the balance, but amount by the mes-- instru-ments, has a field In 0!( er'to determine whenthe currents in -,the; real and'artificial lines'areequal, it is usually thecustom to observe-the effect of be employed at a station for the pur ose of iicial lines but it also indicates whether any particular adjustment of the artificial lines s made inthe proper direction to make the currents in said lines more nearly alike. It has beencustomary in some cases to connect the beginning of "the real line and the be ning of the'arti cial' line through a graft nometer for the impose of determiningwhen a balance has beenob-tained. Such methods, however, do not furnish an exact means of to little more than rendering visible the kicks of the main line relay caused by the reversals of the current. I

- Myinventionfurnishes a method of indicating when the balance is perfect by means of the indicating needles of electrical measur:

ingyinstruments of the dynamometer t pe.

iIy invention also furnishes amet 0d of indicating the character of the adjustment necessar to produce a balance by indicating separate y the vcapacity adjustment and the resistance adjustment of the line. i

Mosthigh speed systems em 10y reverse current signals, while some emplhymodified alternating currents. Since any current reversed at intervals may be considered amore or less complicated combination of alternating-currents of different phaseafi'equencies and amplitudes, and since-a .sim-- ple alternating current furnishes the most convenient 'and sim le method of determining the theory of his method; I shall deingcurrent; V

The essential feature of this method consists in the employment of, at least, two indi- 'cating instruments having electrical fields produced by local means and having movable coils vwhich are in circuit between the' beginning of the real line and the be mum of the artificial line and at least one 0% whic I produced by the sig naling current itself. w i "In Order to more fully describe my invention reference will be had to the accompanying drawings, in which v Figures 1 to 6 inclusive are diagrams show ing the arrangement of circuits which may determining the balance between t e real and theartifici-al lines; and Figs. 7 and 8 are diagrams showing the: hase relations of the currentsin the several ocal circuits.

Referring first to the arrangement shown.

in Fig. 1, M indicates therclay magnet hav-. 11,0

condenser c in circuit therewith.

ing its coils 7c and k oppositely wound and connected respectively in the real or mam line L and the artificial line; or local circuit A which is ounded as indicated at G. The artificial e contains an adjustable resistance' R and a condenser C composed of a number of elements 0, more or less of which may be connected in circuit for the pu ose of adjustment in obtaining a balance. wo indicating instruments of the electro-dynamometer igpe, having field coils F and movable coils and D, are pivotally mounted to sw' within the influence of said fields and provided with needles or pointers p. It will be observed that the field co s of the instruments are joined in parallel in the transmitting circuit before 'it reaches the point of divergence E between the real and artificial lines. The movable coils B andD are-connected in parallel across from the be- 'ng of the real line to the beginning f the artificial line, a resistance r and a co denser 0 being connected respectively in circuit with the coil B and the coil D. In balancing the circuits so that the outgoing current have no effect upon the relay, the artificial line is. adjusted until the two pointers, rest at zero on their scales.

The necessity for the use of two indicating instruments w1ll be evident 'by referri to certain rinci les which may be better ifiustrated y re erring to the phase dia ams shown in Figs. 7 and 8. Re erring to ig. 7, letthe curves land a re resent, respectivel the currents through t e real line and t e artificial line. The curve a, the sum of l and a, will then represent the current from the transmitting station 'which flows throu h the fixedcoils F of the instruments. The curve, b, representing the difference between the currents land a, will indicate the current flowing through the movable coil B except for the amplitude which will depend u on the im edance in series with the coil. he curve represents the current, except for the amplitude through the movable coil- D, being 90 e recs-in phase in advance of the current in t e coil B due to the effect of the Since the currents in the field coils F and the coil B are in phase, while the current in the coil -D 1s in quadrature with the current in the field coils, a deflection will be indicated by the needle p but no deflection will be indicated by the needle p. It is evident, therefore, that the pointer p attached to the coil D'could not alone give a correct indication of the equality and similarity of the currents at the beginning of the real and the artificial lines. -An exact indication of the currents in the two lines can, however, be obtained b my method which will be better understoo by reference to the phase diagram shown m- Fig. 8. As before, hand a represent, respectively, the curren'ts at the that the currents in the fixed an :iuadrature while the cur-- be inmn' g of the real line and the begm' ning of the artificial line. Let it be assumed that the adjustments have been so made that there will be a differenceof phase of 120 degrees between these'currents. If the two currents are equal in value, 8 will represent the phase of the current in the fixed coil F of the two instruments andthe curve b will represent in phase the difference between I and a, or the phase of the'current in the movable coil B. Inasmuch as said curveb is 90 degrees in phase in advance of the current 8, it is evident that curve 8 also represents the phase of the current in the movable .coil D.-

Now since currents in the coils B and D differ in phase by 90 degrees and since the curve aiepresents the phase of the current in the fixed field coils and also in the movable coil D, it is evident that there may be a deflection of inter p attached to 0011 D, and there will. no deflection of inter attached to coil B. It will be seen v consideration that the use of the coil B alone would not completely indicate a balance, since zero deflection would simpl indicate coils were in rents through e two coils of the relay might difler in value and there might he therefore, an actual difference of potenti 'atthe beginningof the artificial and real lines. 'In the case considered, the adjustment of the artificial line has been assumed such that the currents represented -by curves 1 and a have equal amplitudes and differ only in phase, but this has been assumed merely for convenience. If these amplitudes had been assumed to be different, there would be a different phase relation of l and afor a hase difference of 1 90 between a and b.

oil B would indicate zero deflection evenwhen the currents were not alike; There will, therefore, be a varyinfissensibility of the insti'uments havin the 00 B and D respective pen ing upon the amplitudes and phase relations of the two currents. However, when one instrument has its maximum sensibility the other has its minimum sensibility.

From a consideration of the above examples, it is clear that two instruments are necessary to completely determine the balance between the real and artificial lines for an alternating current. A consideration of the above examples has thus shown that there is a certain relation in which the needle p gives no indication of an unbalanced condition and again that there ma be a condition of values in which the use le 1) will give no indication of an unbalanced condition. It is clear, therefore that two instruments are necessary to completely determine the balance between the real lines for an alternating current.

There are various modifications om this as, the art cial line is adjusted, de-.

movable rangement chm described for out be made y considerin certain points of East in the alarming ofthe rey for uplei:- telegraplliy. v v

' In sen telegrap 'o' signals it is usual tor the "to consist of impu e ofvaryingde in opposite directions, so that.

.mLinvention. In Fi'gjrlh Show: the

titration of: a reactance-or self-induction coil 1,. for th'e condenser in series with the coil D; for the purpose or establishing edifference of phase between the currents in the movable coils of. the 'twoin'etmments. Any arrangement which establishes these phase" differences will accomplish in a more or lesshave found that it is not necessary inall cases to em loy electric-magnets forthe fixed will ofbo be I d f manent magnet may 'empo e in one o the instruments, as shown at Pin Fig. 5. It will be ap event that thia-suhatitutioncan taking any given. signals, there iii-usually a preponderance of current in one direction orer that in the other.v For instance; in the lowland system, when no signals are being; sent, alternating currents of diiferent frequency are flowing in the line and the signals consist in areversal, of certain combinations.

in the alternations or half waves. In such stems there" are two different efiects of the signal. upon the main line relay, one of these being a regular vibration oi the rela due to the alternating current, and the ot croonaieting'of distinct kicks of the relay due to l the reversed half waves.

The removal: of these so-called kicks in. balancing is quite rtant.

- 'will'now describe how my method affinds a means of separating the two effects mentioned, so that one needle indicates the balance due to the regular alternating current, and the other needle indicates the reversal of the kicks and, furthermore, one

needle indicatesthe-balance of. the capacity current and the other indicates the balance of thpresistance current.

In Fig- 5, the instrument on the left has hired eleetro-magnetic coils, as in the precedingfigures, while theinstrument on-the right has its field furnished by the rmanent magnet I". The two movable coi B and D are in series with each other and a resistance r and are connected across. from the beginning of the real line to the-beginning of the artificlal line. Now if signals-are sent which 'puoducea pmponderance ofcunentin one instruments,- but: that a perin the ca dimctio'nrt-hem'will be'a defiection'of the neethe he adjusted so that there will be no preof the OOiID-x The artificial lme cranes of: current in one direction over that in the other, as will be when theinter 1/ rem deflection. The use le of thecoil B will indicate the pm once 0 an alternating' current or' rave impuhea It will. be seen that the- 001] D takes the placeoithe-coil D in the ment 1, aeit furnishes-an tional guide in adjusting theline, and catee' an unbalanced line when the conditionsam-sneh-asto o the coiLB. I; have found that the 1n the anangmnent shown in. Fig: 5,:mdl08iil the capacity adjustment of thet'line and coil- D the resistance adjustmant,theaemdications be practically independent. I

reduce the sensibilig of v have also foun that the coil '13 indicates the at vibrations of the icky-due tothealtemating current, and the coil D indicates the reversals or kicks dueto reversed err-modified wavea In my instruments iii-actual prac tice, I contemplate having a: mounted upon the instrument, sothat he one position the coils-will; beconnected. as' shown in; l,.with= analternatingcum-ent supplied tothe field-magnets, IDdFiD-lihfl other pontien of the one of. the instruments as D-wilhbe supplied w'itli av constant field', either by a permanent magnet as shown-in Fig. 5,.or'by the field coils to e direct-current 'en theswitchis in the: latter positionthe resistance ofithe artificial line willbe adjusted until the'needle'pf indicates zero deflection; The'ewitchi ia then changsd to the first ion, and, the msist'ance mmaining unc anged, an ad'ustment is made city ofthe art' cial until the fidleao the-twainstruments indicatelero action. is ,arrangment one sition of the mute will give an indicatio d at the resistance djustment and the other switch position i '11 give the capacity adjustment by means of the indication obtained from the two needles. Although a fair indication of the capaeit adjustment may be obtained-b means 0 3 one needle,it is more accurate,. or the reasons above stated',- to take the indications of the two instruments- In order that the lines may be balanced while signals are being received from the dietant station, I may employ the arrangement disclosed in Fig; 6. In this case the-indicatmg instruments-are connected in circuit only for a certainintervalof-time. In systems -where the signals transmitted from thetwo ends of the line are synchronous, it-ia le to arrange the commutator segment on one i of. the synchronously rotating parts, and a corresponding. commutator segment on the opposite end of the line, so that the mentz may be connected in: circuit at timeswhen there is no received current and the balance may be obtained-by the method above describe It will be understood that while I have illustrated and particularly described certainapparatus and arrangement of circuits for the purpose of segregat ng or separately indicating'the characteristics or constants of the circuits to be balanced, I do not wish to be restricted thereby, but intend to cover all modifications and arran ements which will beapparent to thoseskil ed in the art for effectin the same result. It is also evident that ma employ the method above described in balancing or,indipating the condition of electric circuits other than thoseeniv ity of the constants in the each is indicated.

claim as my inv ntion, and desire to secure by Letters Patent in the United States,-

- l. The method of balancing a plurality of electric circuits, which consists in se arately indicating the relative eflects of the different p'lciyed in systems of te egraphy.

constants of the circuits, and chan ing the values of said constants until a ba ance of 2. The method of balancing'a plurality of electric circuits, which consists in segregating the'efiects of the different constants of the circuits, and changing the values of the constants'of one circuit until a balance or equalcircuits is indicated.

3. The method of balancing a plurality of electriccircuits which consists in connecting a plur lity of indicating instruments between said fc cuits, dephasing the currents flowing in saidinstruments, and adjusting the con-- stants of thecircuits until a balance is indicated. r

4. The method of balancing a plurality of electric circuits which consists in connecting a plurality of indicating instruments of the electrordynamic type between said circuits, dephasing the currents flowing in the movab e elements of said instruments, and adjusta ing the constants of the circuits until a balanceis indicated.

5'. The method of balancing a plurality of electric circuits which consists in affecting a plurality of indicating instruments by currents flowing insaid circuits, causing said instruments to respond to difl'erent constants of said circuits, and adjusting the copstants of one circuit until a balance or equality is indicated by each instrument.

6. The method of balancing a plurality of electric circuits which consists in affecting a plurality of indicating instruments byourrents flowing in said .,c1rcuits, causing one of said nstruments to respond to changes in the value of the currents of said circuits, and

' another instrument to respond to changes in thephase relation of the currents in said circuits, and adjusting the constants of one circuit until a balance or equality is indicated by each instrument.

7. The method of balancing a plurality of electric circuits which consists in affecting a plurality of indicating instruments by currents flowing in said circuits,- causing one of. said instruments to respond to changes in the relative resistance of said circuits and another instrument to respond to changes in the capacity or condenser effect of said circuits, and adjusting the constants of one circuit until a balance or equality is indicated by each instrument.

8. In a system' of telegraphy, means for indicating a balance of the constants-of the circuits, comprising a plurality of indicating instruments connected between said circuits; and means for displacing the phase of the currents flowing in the instruments.

9. In a s stem of telegraphy, means for indicating a alance of the constants of the circuits, comprising a plurality of indicating instruments connected between said circuits;

means for causing one of said instruments to take a current in phase with the potential across said circuits and means for causing another instrument to take a current in quadrature thereto.

- 10. In a s stem of telegraphy, maans for indicating a alance of the constantsof the circuits, comprising a plurality of indicating instruments connected between I said circuits; and means in said circuits whereby one instrument has a maximum vsensibilit and another instrument a minimum senslbility. 11. Ina system of telegraphy, means for indicating a balance of the constants of the circuits, comprising a plurality of indicating instruments connected between said circuits; means for causing one instrument to indicate changes in the relative resistanceof said circuits and means for causing another instrument to indicate changes in the phase relation of currents in said circuits.

12. Ina, system of duplex telegraphy having real and artificial lines, the combination of a pair of indicating instruments of the electro-dynamometer type having their movable elements connected across said lines,-

means for causing one instrument to indicate changes in the relative resistane of said lines, and means for causing the 0th instrument to indicate changes in the relative capacity or condenser effects of said lines.

13. In a system of duplex telegraphy having real and artificial lines, the combination of a pair of indicating instruments of the electro-dynamometer type having their mov.- able elements connected across said lines,

' means for causing one instrument to indicate changes in the relative resistance of said lines, means for causing theother instrument to indicate chan es in the relative capacity or condenser e ects of said lines, and

means for adjusting the resistance and capacity of said artificial line.

14. In a systemfof duplex telegraphy having real and artificial lines, the combination ofa pair of indicating instruments of the electro-dynamometer type having their movable elements connected across said lines,

v one of said instruments having a field excited elecltro-dynamometer type having their mov able elements connected across said lines one of said instruments having a field excited by thecurrent of said system and the other instrument having apermanently magnet ized field, and means for periodically connectin and disconnecting the circuit of the movab e elements. i

In testimony whereof, I aflix my signature,

in presence of two witnesses.

LOUIS M. ro'r'rs Witnesses:

JonN R. HOOPER, W. H. YEATMAN. 

